Belt Scale Vs Bulk Scan article

Conventional conveyor belt scales – also called weightometers – have been around for decades. These mechanical devices measure the volume and speed of bulk media conveyed, with relative accuracy. However, if they are not correctly maintained, the measurement accuracy of the scales may be affected. 

Enter the volumetric belt scanner, equipped with laser measurement technology. It overcomes the challenges faced by conventional weightometers, delivering a number of benefits, including reliable measurement, improved accuracy and reduced maintenance requirements. 

 

SICK Automation’s laser measurement technology solution for measuring bulk conveyed material is Bulkscan®, a flow sensor that uses non-contact time-of-flight technology to measure the volume flow of bulk materials on conveyor belts. Irrespective of the conveyed materials’ properties and ambient weather conditions, Bulkscan® generates a reliable volume flow signal based on the laser’s time of flight. The belt speed is measured using an encoder device (either a wheel encoder or a non-contact Speetec encoder from SICK). The system records the total quantity, calculates the mass flow, and it comes with an integrated function for determining the bulk material’s centre of gravity. This enables it to detect uneven loading (which may cause excessive belt wear).

 

 

 

 

Other physical properties to evaluate when using belt scales include belt width, type, mass per metre and flexibility, as well as conveyor tension profile speed and troughing angles. 

 

When using Bulkscan, the evaluation of these properties plays a minimal role. This is because the inherent laser technology allows for compensation during installation and commissioning, which contributes to a faster, less engineering intensive installation. In addition, the virtual imaging of the material profile done by Bulkscan means that minor changes in moisture and lump size do not affect the overall reading of the material. SICK’s speed feedback device can be included in any Bulkscan installation, enabling the scanner to easily monitor the material flow rates, even under changing conditions. Detailed feedback is forwarded to the conveyor control system on a continuous basis.

 

 

Another challenge in achieving accurate, reliable weighing results with belt scales is that it can be difficult to maintain ‘just-installed’ accuracy without regular calibration (which can become costly). In addition, the recalibration requires that materials of a predefined mass be run during non-production times to calibrate the scales – usually required at set intervals – resulting in extended production downtime.

The only time that laser technology may be similarly affected is if a conveyor system undergoes major mechanical changes. When this is the case, recalibration is required, but it is a fast, simple, painless procedure. Laser technology maintains its accuracy without recalibration as mounting and measurement points are easily adjusted to suit the application. Once Bulkscan has the correct volumetric measurement programmed no further calibration is required. 

 

An additional factor that determines weighing accuracy is the ability of the measurement/weighing equipment to detect and report on integral failure. Bulkscan from SICK offers comprehensive onboard diagnostics, providing network feedback of system functionality and measurement quality to a customer’s control room. This reporting method allows for intervention prior to critical failure occurring, drastically minimising the threat of unplanned downtime. The same holds true in the event of electronic failure. The diagnostics tools in Bulkscan’s software triggers a failure alarm, but this is rarely the case as the equipment incorporates a maintenance alarm too. This notifies operators of a potential event, allowing action to be taken and a failure prevented. Consider this your cost-effective, ‘zero-downtime preventative maintenance’ solution.

 

Taking all this into consideration, the outlook for the uptake of scanning technology to measure the volume, mass flow and speed of conveyed bulk material seems positive.